Air or other pressurized gas is commonly introduced into dry bulk material to fluidize the material for efficient pneumatic transfer through vessels such as ducts, hoppers, tanks, bins, silos, bulk carrier dischargers, and the like. Because the materials are being transported in bulk, and are prone to bind or pack against non-smooth surfaces, such vessels are characterized by smooth curved surfaces, i.e., circular cross-sections having large diameters. To be effective, aerators must not only introduce the air or other gas into the vessel, but must do so while introducing a degree of vibration to the vessel and material, along with a dispersion of the air supply into the vessel.
One popular type of aerator is taught in U.S. Pat. No. 4,662,543 (Solimar). It comprises a resilient flexible disk having an inner conical surface and an outer conical surface. The disk is mounted on a hollow stem having air outlets underneath the disk, such that the aerator may be fastened to a hole in the surface of the vessel to place the disk in a prestressed condition against the inner, curved surface of the vessel. Pressurized gas flows through the hollow stem through the air outlets to the interior of the vessel, beneath the disk, and then outwardly past the interface between the edge of the disk and the inner curved surface of the vessel. This causes the edge of the disk to vibrate as the gas passes by.
There is, therefore, an interrelationship between the resiliency and flexibility of the disk, the diameter of the vessel surface, and the gas pressure, that dictate whether an aerator is effective for its intended purpose.